Reapply "Use Project instead of Workspace in ContextStore (#28402)" (#28441)

Motivation for this change is to use `ContextStore` in headless
assistant, which requires it to not depend on UI entities like
`Workspace`.

This reapplies a change that was revert was in #28428, and fixes the panic.

Release Notes:

- N/A

crates/agent/src/inline_assistant.rs

@@ -28,6 +28,7 @@ use language_model::{LanguageModelRegistry, report_assistant_event};
 use multi_buffer::MultiBufferRow;
 use parking_lot::Mutex;
 use project::LspAction;
+use project::Project;
 use project::{CodeAction, ProjectTransaction};
 use prompt_store::PromptBuilder;
 use settings::{Settings, SettingsStore};
@@ -254,6 +255,7 @@ impl InlineAssistant {
                         assistant.assist(
                             &active_editor,
                             cx.entity().downgrade(),
+                            workspace.project().downgrade(),
                             thread_store,
                             window,
                             cx,
@@ -265,6 +267,7 @@ impl InlineAssistant {
                         assistant.assist(
                             &active_terminal,
                             cx.entity().downgrade(),
+                            workspace.project().downgrade(),
                             thread_store,
                             window,
                             cx,
@@ -318,6 +321,7 @@ impl InlineAssistant {
         &mut self,
         editor: &Entity<Editor>,
         workspace: WeakEntity<Workspace>,
+        project: WeakEntity<Project>,
         thread_store: Option<WeakEntity<ThreadStore>>,
         window: &mut Window,
         cx: &mut App,
@@ -425,7 +429,7 @@ impl InlineAssistant {
         for range in codegen_ranges {
             let assist_id = self.next_assist_id.post_inc();
             let context_store =
-                cx.new(|_cx| ContextStore::new(workspace.clone(), thread_store.clone()));
+                cx.new(|_cx| ContextStore::new(project.clone(), thread_store.clone()));
             let codegen = cx.new(|cx| {
                 BufferCodegen::new(
                     editor.read(cx).buffer().clone(),
@@ -519,7 +523,7 @@ impl InlineAssistant {
         initial_prompt: String,
         initial_transaction_id: Option<TransactionId>,
         focus: bool,
-        workspace: WeakEntity<Workspace>,
+        workspace: Entity<Workspace>,
         thread_store: Option<WeakEntity<ThreadStore>>,
         window: &mut Window,
         cx: &mut App,
@@ -537,8 +541,8 @@ impl InlineAssistant {
             range.end = range.end.bias_right(&snapshot);
         }
 
-        let context_store =
-            cx.new(|_cx| ContextStore::new(workspace.clone(), thread_store.clone()));
+        let project = workspace.read(cx).project().downgrade();
+        let context_store = cx.new(|_cx| ContextStore::new(project, thread_store.clone()));
 
         let codegen = cx.new(|cx| {
             BufferCodegen::new(
@@ -562,7 +566,7 @@ impl InlineAssistant {
                 codegen.clone(),
                 self.fs.clone(),
                 context_store,
-                workspace.clone(),
+                workspace.downgrade(),
                 thread_store,
                 window,
                 cx,
@@ -589,7 +593,7 @@ impl InlineAssistant {
                 end_block_id,
                 range,
                 codegen.clone(),
-                workspace.clone(),
+                workspace.downgrade(),
                 window,
                 cx,
             ),
@@ -1779,6 +1783,7 @@ impl CodeActionProvider for AssistantCodeActionProvider {
         let workspace = self.workspace.clone();
         let thread_store = self.thread_store.clone();
         window.spawn(cx, async move |cx| {
+            let workspace = workspace.upgrade().context("workspace was released")?;
             let editor = editor.upgrade().context("editor was released")?;
             let range = editor
                 .update(cx, |editor, cx| {